You should follow the change interval recommended by the vehicle manufacturer, as stated in the "Owner's Manual". Current engine manufacturers are suggesting increasingly longer change intervals, depending on the type of service and maintenance of the car.

Contrary to what most people think, the correct level is between the two marks on the dipstick, not just at the upper mark. If the oil is below the minimum mark on the dipstick, the engine could suffer damage due to lack of lubrication. However, if the oil is above the maximum mark, it could lead to increased pressure in the crankcase, potentially causing leaks or even connecting rod failure. Additionally, excess oil could burn in the combustion chamber, fouling spark plugs and valves, and also damaging the catalytic converter in the vehicle's exhaust system.

With car usage, the oil level decreases slightly due to engine clearances and partial combustion in the combustion chamber. Therefore, until it's time to change the oil, you should keep topping up the oil level.

You should change the oil according to the recommended interval by the vehicle manufacturer in the "Owner's Manual". Modern engine manufacturers are extending change intervals, depending on the type of service and maintenance of the car.

Yes, because when the oil is warm, it becomes thinner and flows more easily.

Yes, you should change the oil filter. The oil, with its detergent/dispersant additives, carries impurities that would otherwise deposit in the engine. As it passes through the filter, larger impurities are trapped, while smaller ones remain suspended in the oil. Eventually, the filter becomes clogged with dirt, impeding oil flow and causing lubrication failures. The situation worsens when the oil filter is completely blocked, which can result in severe engine damage. The oil filter change interval is also recommended by the vehicle manufacturer and is listed in the "Owner's Manual". Typically, it's advised to change it with every oil change.

"Severe service" refers to cars operating in challenging conditions, such as urban driving with frequent stops and starts or on dusty roads. "Light service" applies to cars that travel long distances at almost constant speeds on paved roads, like highway driving.